Ventilation and areation device for a fuel tank

ABSTRACT

The invention relates to a ventilation and aeration device for a fuel tank ( 1 ) of a motor vehicle, comprising a ventilation line ( 9 ) leading to the exterior of the fuel tank ( 1 ); said ventilation line being connected to the inner area ( 18 ) of the fuel tank ( 1 ) via a ventilation opening ( 16 ) of a ventilation link having a larger throughflow diameter and an aeration opening ( 21 ) of an aeration link having a smaller throughflow diameter. The ventilation opening ( 16 ) leads into the inner area of the fuel tank ( 18 ) at a filling level height ( 17 ) which is lower than that of the aeration opening ( 19 ) of the aeration link. A roll-over valve ( 10 ) is used to seal off the inner area ( 18 ) of the fuel tank ( 1 ) in relation to the ventilation line ( 9 ). The ventilation link and the aeration lead to a common ventilation channel ( 20 ) leading to a single roll-over valve ( 10 ) whose outlet is connected to the ventilation line ( 9 ).

BACKGROUND OF THE INVENTION

[0001] The invention is concerned with a ventilation and aeration devicefor a fuel tank, in particular of a motor vehicle, having a ventilationline which leads to the exterior of the fuel tank and is connected tothe inner area of the fuel tank via a ventilation opening of aventilation link of larger through-flow cross section and an aerationopening of an aeration link of smaller through-flow cross section, theventilation opening of the ventilation link leading into the inner areaof the fuel tank at a filling level height which is lower than theaeration opening of the aeration link, and a roll-over valve being usedto seal off the inner area of the fuel tank from the ventilation line.

[0002] In the case of ventilation and aeration devices of this type, theventilation opening and ventilation link are used to conduct gas whichhas been displaced in the fuel tank by the fuel fed in during arefueling process to the outside. If, during the refueling process, thefilling level reaches the level of the ventilation opening and thelatter is covered in the process by the fuel, gas can no longer beconducted away through the ventilation opening. The fuel which flows infrom the refueling and acts on the rest of the volume of gas in the fueltank causes a pressure to be built up in the fuel tank, the pressureacting on the tank nozzle introduced into the filler neck of the fueltank and actuating the automatic cutoff contained in this tank nozzle.Further filling of the fuel tank is therefore terminated.

[0003] The aeration opening, which is situated higher than theventilation opening, has only a small cross section which acts as athrottle and through which gas cannot be conducted away sufficiently inorder to prevent the described build-up of pressure during refueling.

[0004] The ventilation opening serves to conduct away a volume of gas,which becomes enlarged when there is a rise in temperature, to theoutside, so that a rise in pressure in the fuel tank does not takeplace.

[0005] In order to prevent fuel from being able to run out of the fueltank via the ventilation and aeration openings if the motor vehicle isin an accident and overturns, the roll-over valves seal off theventilation and aeration openings in the corresponding position of themotor vehicle.

[0006] In the case of a ventilation and aeration device of the typementioned at the beginning, it is known to design both the ventilationopening and the aeration opening in a manner such that they can besealed off in each case by a roll-over valve. The construction of thisventilation and aeration device is very complex and expensive andrequires a large structural space.

[0007] EP 186 372 A discloses a ventilation and aeration device for afuel tank having a ventilation line which leads to the exterior of thefuel tank and is connected to the inner area of the fuel tank via aventilation opening of a ventilation link of larger through-flow crosssection and an aeration opening of an aeration link of smallerthrough-flow cross section. In this case, the ventilation opening of theventilation link leads into the inner area of the fuel tank at a fillinglevel height which is lower than the aeration opening of the aerationlink.

[0008] U.S. Pat. No. 5,215,132 A discloses a ventilation and aerationdevice for a fuel tank, having a ventilation line which leads to theexterior of the fuel tank and is connected to the inner area of the fueltank via a ventilation opening of a ventilation link of largerthrough-flow cross section and a further ventilation opening. Theventilation line can be sealed off from the inner area of the fuel tankby a first roll-over valve, to the outlet of which the ventilation lineis connected. A second ventilation line leading to the exterior of thefuel tank can be sealed off by a second roll-over valve.

[0009] The object of the invention is therefore to provide a ventilationand aeration device of the type mentioned at the beginning which has asimple construction and requires only a small structural space.

BRIEF DESCRIPTION OF THE INVENTION

[0010] This object is achieved according to the invention by the factthat the ventilation link and aeration link lead into a commonventilation channel which leads to a single roll-over valve, to theoutlet of which the ventilation line is connected.

[0011] By bringing the ventilation link and aeration link togetherupstream of the roll-over valve, it is possible to omit a secondroll-over valve, this resulting in a considerable simplification andcost reduction and also in a reduction in the required installationspace.

[0012] A single ventilation line then leads from the roll-over valveeither to the filler neck of the fuel tank and from there on via anactivated carbon filter to the outside. However, the ventilation linemay also be led directly via an activated carbon filter to the outside.

[0013] In one simple design, the ventilation link may be a ventilationpipe which protrudes into the fuel tank and the inner area of which isconnected via the ventilation opening to the inner area of the fueltank.

[0014] If, in addition, the aeration opening is a continuous radialrecess in the ventilation pipe, said, recess connecting the inner areaof the fuel tank to the inner area of the ventilation pipe at a fillinglevel height which is higher than the ventilation opening, then noadditional components and no additional structural space are requiredfor the aeration.

[0015] In a further, likewise simply constructed variant, the aerationopening can be an aeration pipe of smaller cross section than the crosssection of the ventilation pipe.

[0016] In this case, no additional structural space is required if theventilation pipe and the aeration pipe extend axially, in particularcoaxially, into the inner area of the fuel tank.

[0017] In order to ensure that there is sufficient space for a minimumvolume of gas in a fully refueled fuel tank, the ventilation opening canlead into the inner area of the fuel tank approximately at a fillinglevel height of 85% to 90% of the entire volume of said fuel tank.

[0018] If the aeration opening leads into the inner area of the fueltank close to the highest point of said fuel tank, then an aeration ofthe tank under largely all operating conditions of the motor vehicle isensured.

[0019] A bubble-type extraction tank can be arranged downstream of theroll-over valve in the ventilation line and is used to separate off fuelparticles contained in the gas conducted away from the fuel tank and toreturn them to the fuel tank.

[0020] If the roll-over valve is arranged within the fuel tank, then thequantity of fuel which penetrates by means of permeation to outside thefuel tank is kept particularly small.

[0021] However, the roll-over valve may also be arranged outside thefuel tank.

[0022] The roll-over valve preferably has a passage opening which can beclosed by a closing element and leads from the ventilation channel tothe ventilation line, it being possible for the closing element to beacted upon in the closing direction by a gravity-loaded body and/or afloating body. If the motor vehicle is upside-down, the gravity-loadedbody subjects the closing element to its weight and keeps said closingelement on the passage opening, with the result that fuel cannot runout. The floating body is used to act upon the closing element in amanner closing the passage opening if the fuel in the fuel tank shouldrise to such an extent that the floating body is caused to float.

[0023] The ventilation line may lead directly to an activated carbonfilter or else to a filler neck of the fuel tank 20 and from there ontoan activated carbon filter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] An exemplary embodiment of the invention is illustrated in thedrawing and will be described in greater detail below. In the drawing

[0025]FIG. 1 shows, in section, a detail of a side view of a fuel tankhaving a ventilation and aeration device

[0026]FIG. 2 shows an enlarged illustration of the ventilation andaeration device according to FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0027] The fuel tank 1 which is illustrated in FIG. 1 has, on its upperwall 2, an opening 3 (see FIG. 2) into which a ventilation and aerationdevice 4 is inserted closing the opening 3. Furthermore, the fuel tank 1has a filler neck 5 leading in its right-hand, upper region.

[0028] The ventilation and aeration device 4 has a cover part 6 with aflange 7, which cover part can be inserted into the opening 3 until theflange 7 rests on the upper wall 2, and by means of which the opening 3can be closed.

[0029] A connecting branch 8 which leads outward and has a ventilationline leading to the exterior of the fuel tank 1 is formed integrally onthe cover part 6. The tank-side end of the ventilation line 9 is apassage opening 11 which is designed as a valve seat of a roll-overvalve 10 and can be closed by a closing element 12. The closing element12 is moved in the direction of the tank exterior for closing purposes.

[0030] Coaxially with the passage opening 11, a ventilation pipe 13extends approximately vertically into the inner area 18 of the fuel tank1, said ventilation pipe being fastened at its upper end to the coverpart 6 and forming a guide for the closing element 12.

[0031] Furthermore, on that side of the closing element 12 which facesaway from the passage opening 11, a freely movable ball forming agravity-loaded body 14 is arranged in the ventilation pipe 13 and, givenan appropriate upside-down position of the tank, subjects the closingelement 12 to the force of its weight pushing it against the valve seatof the passage opening 11 and closes the latter.

[0032] In order to keep the ball close to the closing element 12, a grid15 is arranged below the ball in the ventilation pipe 13, the grid,however, only insignificantly reducing the passage cross section of theventilation pipe 13.

[0033] The ventilation pipe 13 leads with its ventilation opening 16into the inner area 18 of the fuel tank 1 at a filling level height 17of 85% of the entire volume of said fuel tank.

[0034] A continuous recess is formed directed radially in theventilation pipe 13 at the height of the closing element 12 close to thehighest point of the fuel tank 1, said recess forming an aeration link19 which leads with its aeration opening 21 into the inner area 18 ofthe fuel tank 1. The region in the ventilation pipe 13 between theaeration link 19 and the passage opening 11 forms a ventilation channel20, into which the gas entering into the ventilation pipe 13 from theinner area 18 of the fuel tank 1 via the ventilation opening 16 and theventilation opening 21 is jointly supplied via the roll-over valve 10and the passage opening 11 of the ventilation line 9.

[0035] The ventilation opening 16 has a considerably larger passagecross section than the aeration opening 21 acting as a throttle, so thatgas which is to be displaced during refueling can be conducted awaywithout obstruction via the ventilation opening 16 as long as thisventilation opening 16 is not yet covered by the fuel in the fuel tank 1and is therefore sealed off. However, volumes of gas of this type whichare displaced during refueling are too large to be able to be conductedaway via the remaining aeration opening 21, and so a pressure which cutsoff the fuel nozzle builds' up in the fuel tank 1.

[0036] The ventilation line 9 leads on from the connecting branch 8 viaa bubble-type extraction tank 22 to the filler neck 5 where it leadsinto its upper end. Fuel particles contained in the gas are separatedoff by the bubble-type extraction tank and returned via the ventilationline 9 and the open roll-over valve 10 into the inner area 18 of thefuel tank 1.

1. A ventilation and aeration device for a fuel tank, in particular of amotor vehicle, having a ventilation line which leads to the exterior ofthe fuel tank and is connected to the inner area of the fuel tank via aventilation opening of a ventilation link of larger through-flow crosssection and an aeration opening of an aeration link of smallerthrough-flow cross section, the ventilation opening of the ventilationlink leading into the inner area of the fuel tank at a filling levelheight which is lower than the aeration opening of the aeration link,and a, roll-over valve being used to seal off the inner area of the fueltank from the ventilation line, characterized in that the ventilationlink and aeration link lead into a common ventilation channel (20) whichleads to the single roll-over valve (10), the outlet of which isconnected to the ventilation line (9).
 2. The ventilation and aerationdevice as claimed in claim 1, characterized in that the ventilation linkis a ventilation pipe (13) which protrudes into the fuel tank (1) andthe inner area of which is connected via the ventilation opening (16) tothe inner area (18) of the fuel tank (1).
 3. The ventilation andaeration device as claimed in claim 2, characterized in that theaeration opening (21) is a continuous radial recess in the ventilationpipe (13), said recess connecting the inner area (18) of the fuel tank(1) to the inner area of the ventilation pipe (13) at a filling levelheight which is higher than the ventilation opening (16).
 4. Theventilation and aeration device as claimed in claim 2, characterized inthat the aeration opening is an aeration pipe of smaller cross sectionthan the cross section of the ventilation pipe.
 5. The ventilation andaeration device as claimed in claim 4, characterized in that theventilation pipe and the aeration pipe extend axially, in particularcoaxially, into the inner area of the fuel tank.
 6. The ventilation andaeration device as defined in claim 2, wherein the ventilation opening(16) leads into the inner area (18) of the fuel tank (1) approximatelyat a filling level height (17) of 85% to 90% of the entire volume ofsaid fuel tank.
 7. The ventilation and aeration device as defined inclaim 1, wherein the aeration opening (21) leads into the inner area(18) of the fuel tank (1) close to the highest point of said fuel tank.8. The ventilation and aeration device as defined in claim 1, wherein abubble-type extraction tank (22) is arranged downstream of the roll-overvalve (10) in the ventilation line (9).
 9. The ventilation and aerationdevice as defined in claim 1, wherein the roll-over valve (10) isarranged within the fuel tank.
 10. The ventilation and aeration deviceas defined in claim 1, wherein the roll-over valve is arranged outsidethe fuel tank.
 11. The ventilation and aeration device as defined inclaim 1, wherein claimed in one of the preceding claims, characterizedin that the roll-over valve (10) has a floating closing element (12) tobe acted upon in the closing direction by a gravity-loaded body (14).12. The ventilation and aeration device as defined in claim 1, whereinthe ventilation line (9) leads to an activated carbon filter.
 13. Theventilation and aeration device as defined in claim 1, wherein theventilation line (9) leads to a filler neck (5) of the fuel tank (1).